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The brain is part of the central nervous system. - The brain and spinal cord make up the central nervous system. This is the largest part of the nervous system. The adult brain weighs about three pounds.
- The peripheral nervous system consists of nerves, which are bundles of neurons. Your peripheral nervous system helps connect your central nervous system to the rest of your body.
- Neurons and glial cells are the two primary cell types in nervous tissue. Neurons convey nerve messages. Neurons are surrounded by glial cells, which help protect them.
- Input to the nervous system is recognized by our senses: smell, vision, taste and hearing. Organisms also recognize pain, pressure and temperature, which are referred to as the somatic senses.
- Your body has around 30,000 million nerve cells, which can each transmit 1,000 nerve impulses per second. The number of nerve cells in the human brain is larger than the number of stars in the Milky Way galaxy.













